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This is the continuation of an old thread that is now locked for editing.

Several people on the forum told me I was underpowering my tops, a pair of EV SX300 with a Yamaha EMX 512SC powered mixer and suggested I buy a new amplifier.

I walked into a store today and spoke with the owner who said
1. The EV SX300s are rated 300W @8ohms continuous
2. The Yamaha EMX512SC puts out 350W @8ohms per channel.

3. He even suggested I get another pair of EVs and daisy chain them, but use the same powered mixer if I needed more power.

He said he didn't think I needed another amp. I checked the specs and it turns out he is right about the spec.

I am trying to understand why you guys suggested a bigger amp? Any help you can provide would be great.

Thanks all

Vic in Sydney

The origianl thread wasn't locked for anything, any thread that is not active over a certain time will automatically get moved into the archives.

As far as the speakers, they are rated at 300 continuous at 8 ohms, the amp in question pushes 'maximum' - PEAK 320-350 watts into 8 ohms meaning it's 'clean' power rating is going to be much lower - seriously underpowering the speakers potential. Most sound engineers will tell you to match your speakers to an amp at twice the continuous power rating - in this case 600 watts. This would be technically the 'program'' rating - which many speaker manus now offer - usually twice continous - half peak. Which means for the speakers to operate at the full potential, your amp should be able to push approx 600 watts per channel RMS. Which looking at the other thread (had to do a little search), the knowledgeable engineers suggested, were right on the money in this case!
I never trust salesmen as they are usually working comission & trying to say what you want to hear to get you to get something that won't be of much added benefit 90% of the time. In this case, he said use two more of the same speakers - which would drop them to a 4 ohm load per channel, meaning each side would now need 1200 watts (program) at 4 ohms from the amp - however the EMX512 only pushes 500 watts into 4 ohms. Doubling the speakers will effectively raise the volume a couple decibels, but still won't pull out the untapped potential of the speakers themselves. However if the outdoor situation is still a factor, then a couple of subs would still be a good add.
Sorry, sounds like the salesman (owner) was trying to make another sale.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Lonman

Great information as always. I am considering getting rid of my sub alogether and just buying a pair of Yahama S115V's. I was hoping to use them together with my EVs to get higher levels and me bass from the 15". Ofcourse I would pick up a nice big QSC to power them up.

A large show for me would be 200 people max not spread out too thinly. Any advice for a PA noob?

Thanks
Vic in Sydney

Why would you get rid of your sub?

A QSC PLX 1804 is a good amp for your speakers.

I'd like to add on to Lon's post a little bit. Amplifiers are not designed to run at their peak levels. Simply put the harder you push an amplifier, the worse it performs. As the levels go up in your amplifier, it begins to generate more and more distortion. Distortion is what kills speakers. So using a 350W amplifier to drive speakers whose continuous power handling is 300W means you'll likely be driving that amplifier near 100% of it's capability which results in distortion and possibly clipping (the two most common causes of speaker damage). You're much better off with an amplifier that can push a peak of 700W and run it at about 50% as the amount of distortion introduced would be far less as would the potential for clipping.

I've seen a plenty of speakers that have been damaged for one reason or another. Far more are damaged as a result of under-powering than over-powering.

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DJ Tony
Let It Rip Karaoke

An analogy:

Both a Yugo and a Porche will do 100mph for an extended period of time.

The Yugo will be maxed out, pedal to the floor eventually damaging the engine.
The Porsche will cruise at 100mph all day long with no ill effects and power to spare.

So while we’re on the subject of AMP/Speaker configuration…

Just when I thought I had it straight, I read something to question what I thought I knew.

Ok Here’s how I thought I understood the marriage of the speaker/amplifier thing.

“RMS” I thought was the lowest gage; if doubled becomes “continuous or program”, and when doubled again becomes “Peak”. It seems I have my understanding of “Continuous” and “RMS” reversed.

Having said that, the varying manufacturer specs can be confusing on their own because their terms/standards seem to differ.

Now I’m not attempting to start any debate here; heaven knows I haven’t the extensive background that many here do. I’d just like to know what’s wrong with my understanding of the power terms/standards.

My actual applications are:
QSC RMX 2450, 750w (x2) @ 4 Ohms driving (2) PV215’s Rated 700w each (1400peak) @ 4 Ohms.

And while I thought this was a pretty balanced configuration, I’m not so sure of my sub configuration now:

EV Eliminator I (x2) rated at 400w @ 8 Ohms. The manufacturer’s amplifier power recommendation ranges from 400 to 800w. I currently use a QSC RMX 1450 bridged for 900w 8 Ohms for each sub. This is starting to sound like I’m pushing the limits. Alternatively, I’m thinking that I could use one Amp configured for stereo and connect the subs in parallel from one channel which would give me 400w @ 4 Ohms. Or should I leave it bridged?

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EveningStar Entertainment & Events
JR & Michele LaPorte
Peoria, AZ

This warrants another question. What constitutes pushing your amplifier to its limit?

Correct me please if I’m wrong. But, to me it means (just like the Yugo analogy) all controls are set to maximum.

Now what if you’re pushing this 350w amp and 300w speakers at something less than their maximum power rating?

Example: As I previously posted I sometimes use a QSC RMX 2450, 750w (x2) @ 4 Ohms driving (2) PV215’s Rated 700w each (1400peak) @ 4 Ohms; which, as I mentioned, I thought was a good balance. But based on the information above, I may be pushing my limits here as well. However, shouldn't the mix input to the amp have a direct effect on this?

Again like the Porche I may be doing the 100mph, but my throttle may only be at 35-40%, leaving me plenty of reserve power.

Case-in-point: My amp controls are always maxed out. I set all my mixer input gains just below the level that their yellow peak light comes on (about 11 O’clock or 35-40%). I set my mains at 0db and adjust volume by each channel slider. If a channel should start to clip, I decrease the input gain and increase the channel slider.

As a result, the only time I experienced the clip light on my amp is when I pay the Cha-Cha Slide. (Darn song always gives me fits!!)

So, am I wrong, to the detriment of my equipment, in my application?

Again, I’m not challenging any one’s credibility here. I merely seek to know what’s correct.

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EveningStar Entertainment & Events
JR & Michele LaPorte
Peoria, AZ

Below find some speaker specs and pricing - Minimum Amps should be double the CONTINUOUS x 2 @ 8ohms
SPEAKER Continuous Program Peak Sensitivity Price
Yamaha Sv115V 250w 500w 1,000w 99dB $289.99
Yamaha BR15 125w 250w 500w 98dB $369.99
Peavey SP2 500w 1,000w 2,000w 98dB $499.99
Peavey SP5 400w 800w 1,600w 99dB $399.99
Peavey PR15 200w 400w 800w na $219.94
Behringer B1520pro 200w 400w 800w 96dB $349.99
Ev Eliminator 350w 700w 1,400w 99dB $599.00
Ev TX1152 Tour 500w 1,000w 2000w 100dB $749.00

You QSC Peavey match is fine. It's always better to have a little more power than not enough.
You are doing fine, if that clip light ever comes on, then yes you back down the gains & can compensate with the fader.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Pushing your amp to it's limit isn't necessarily about how you have the input sensitivity on it set. Personally, my amp is always run with the input sensitivity all the way up and that's exactly how we run our line arrays, X arrays and Phoenix systems. In such a case you should be watching the meters on your mixer's main output. If your peaks are jumping up to or close to 0 dbu then you're pretty much maxing out your amp. Typically my meters are somewhere around the -30 dbu mark with peaks maybe getting as high as -20 dbu. That's with an amplifier that's pushing 600W a side. So in the same sized club where that is sufficient, if I had a smaller amp (say 350 a side) I'd have to be pushing those meters higher to achieve the same volume levels and as such introducing more distortion.

As to the question about RMS, continuous and RMS are effectively synonymous. Usually speakers have 3 ratings RMS (continuous), Program and Peak. RMS is the lowest of the three figures, Program is usually about double RMS and Peak is usually double the Program rating. Hope that clears it up.

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DJ Tony
Let It Rip Karaoke

In the "old days" where audio equipment did not have the SNR we enjoy today, that would be a bad plan; but the only thing terribly wrong with it today is you don't really know where your amps clip unless you can see the lights or you set your system gain a bit more carefully.

In fact, +0dBu is not enough to drive most pro-audio amplifiers to maximum power. Most will want at least +5dBu while some common amps won't be driven to full power until they are getting a +10dBu input signal with the knobs and switches all wide open (see the PL380 spec sheet if you don't believe me!)

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Jeff Wheeler, moonlight DJ/KJ

Here's a great tool from QSC, you'll know which amp to use with your EV's

http://www.qscaudio.com/products/amps/a ... lector.htm

You'll see that Lonman & Tony are right

The advice above is right on.

My rule of thumb is you can never have too much power.



Mojo

Wow! What a cool tool! I've been to QSC's site before but hadn't come accross that function. With the info provided there, and based on the earlier RMS Vs. Contiuous clarifiction, and re-reading the specs, my amp/sub configuration looks to be good as well. Thank you all for the valuable input. My confusion is cleared

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EveningStar Entertainment & Events
JR & Michele LaPorte
Peoria, AZ

Jeff, this frustrates me because your just plain wrong. Clipping on the amplifier isn't the only issue here, and I thought we had discussed that at length. If you've got the input sensitivity all the way up and your console is pushing the main out at 0dbu you're pushing your amp pretty close to max. Sure you may not be at full power but the fact is you're running at least at 75% which is NOT GOOD. The harder you push your amps the more distortion gets introduced and the more stress you put on your drivers.

Don't believe me, go to a music concert sometime and watch the meter bridge on the FOH console. They rarely ever get over -20db and if they do usually you'll see the engineers scrambling. The reason is simple, amps are not designed to be driven anywhere close to their peak levels on a consistent basis. Unlike a car engine, amplifiers perform their best when they're kept barely above idle.

I'm 32 and regularly work on EV's X-Array and Phoenix rigs, trust me, my information isn't as antiquated as you'd like to believe it is.

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DJ Tony
Let It Rip Karaoke

If the example amplifier needs +5dBu to reach maximum RMS power then you are closer to 25% power than 75%. Besides that, RMS ratings are just that; and amps have headroom built into them for peaking and keeping the speakers going while the AC line voltage is 0V between cycles.

The clip lights on modern amplifiers mean a very specific and measurable thing. For example, some amps illuminate the clip indicators at 0.1% THD, while others come on at 1% THD. Where it happens does matter, but you can pretty much bet the amp is producing a signal with little or no harmonic distortion when the clip light isn't on.

The real thing you start to audibly hear as a rig gets closer to maximum output is an increase in inter-modulation distortion, or the loudspeakers just outright exceeding Xmax and being unable to accurately reproduce high-frequency content because the driver is significantly outside the voice coil gap. Dave Rat and others have written some good stuff on this topic and it is believed to be a contributing factor, maybe the main reason, as to why "dual PA" sounds so much better than a single PA.

I think the things you think you are hearing because the amplifiers are working hard are in fact distortion created by the loudspeakers, which are probably also working hard as the amps and speakers were likely selected with similar power ratings; but the speaker has a much harder job of producing linear response than the power amp.

If you have never done this, I suggest that you get an amplifier that is really, really under-sized for the speaker it is powering, then drive it to just below clip. Then compare to a bigger amplifier driven to the same output power level on the same speaker.


Woofers with discrete amplifier channels really do not suffer at all from a horribly clipped, distorted input waveform. I guess you are aiming to describe what happens to a speaker with a passive crossover when distorted energy is shifted to the high-frequency drivers; and that is a problem that blows horn drivers in a hurry. I have a dead wedge HF driver in my garage right now because of this.


I don't know any clubs or touring companies that have 20dB of headroom for major shows that don't have an unlimited budget. This is obviously outside the scope of discussion here, but I disagree with you.

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Jeff Wheeler, moonlight DJ/KJ

This is also good to know. "Operate ate -30 or less, and peak no more than -20". While normally I have very little reading on my meter, I can't say that I remember exactly when I have seen it max out. The meter is a string of LEDs, and I can't say that I've ever seen them leave the green. I'll have to pay closer attention from now on though.

Would the meter reading have a direct coorilation to the position of the main sliders or to the combined input of the individual channels?

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EveningStar Entertainment & Events
JR & Michele LaPorte
Peoria, AZ

Assuming the meter is showing the main output (normal if you don't push a PFL/AFL button) it shows just that: the signal present at the main outputs. That signal level can be increased or decreased by the main fader, channel faders, gain knobs, EQ knobs, etc. You can unhook your mixer from the amplifiers and demonstrate this to yourself by playing music or speaking into a microphone and then manipulating those controls.

It's not literally a "volume meter" since that's a bit of a complex subject, but it can be simplified to mean a volume meter before amplification happens.

Given the same settings on your amp, same speakers, same listening position, and same program material, a 10dB increase on the meter will sound about twice as loud, up until you reach the limits of your speakers/amps.

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Jeff Wheeler, moonlight DJ/KJ

Alright everyone - here's what I think I'll do:

1. Buy a Behringer EP4000
2. Use the built in crossover and plug my EV SX300s into the amp.
3. Run the powered sub JBL JRX118SP out of the mixer

This should do the following:
1. Less distortion out of my EVs since (a) they are crossed over nice and pretty (b) they are getting more than enough power from the EP4000.
2. The new amp will give me enough headroom should I want to add another pair of FOH to my setup and run in parallel in future.

My reasoning is as follows:
1. I need to maintain the compact EVSX300's as I have to pack up my PA after every gig. Most of these are small indoor gigs and I probably would not lug the amp to these events.
2. I can lug the amplifier to slightly bigger events to power up the EVs to full potential with a sub.
3. For the 200 pax + gigs, I can add a pair of Yamaha C115V's to the mix for some 15" thump in parallel to my EVs and the powered sub.

Does this make sense, or am I an even bigger noob than ever?

Advice much appreciated.

Vic in Sydney


PS: Behringer EP400 - A$500; QSC G5 - A$1000 + That's why I am considering behringer... :S